In nilfs_gccache_submit_read_data(), brelse(bh) is called to drop the
reference count of bh when the call to nilfs_dat_translate() fails.  If
the reference count hits 0 and its owner page gets unlocked, bh may be
freed.  However, bh->b_page is dereferenced to put the page after that,
which may result in a use-after-free bug.  This patch moves the release
operation after unlocking and putting the page.

NOTE: The function in question is only called in GC, and in combination
with current userland tools, address translation using DAT does not occur
in that function, so the code path that causes this issue will not be
executed.  However, it is possible to run that code path by intentionally
modifying the userland GC library or by calling the GC ioctl directly.

[konishi.ryusuke@gmail.com: NOTE added to the commit log]
Link: https://lkml.kernel.org/r/1543201709-53191-1-git-send-email-bianpan2016@163.com
Link: https://lkml.kernel.org/r/20230921141731.10073-1-konishi.ryusuke@gmail.com
Fixes: a3d93f709e89 ("nilfs2: block cache for garbage collection")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Reported-by: Ferry Meng <mengferry@linux.alibaba.com>
Closes: https://lkml.kernel.org/r/20230818092022.111054-1-mengferry@linux.alibaba.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Pull block updates from Jens Axboe:
 "Pretty quiet round for this release. This contains:

   - Add support for zoned storage to ublk (Andreas, Ming)

   - Series improving performance for drivers that mark themselves as
     needing a blocking context for issue (Bart)

   - Cleanup the flush logic (Chengming)

   - sed opal keyring support (Greg)

   - Fixes and improvements to the integrity support (Jinyoung)

   - Add some exports for bcachefs that we can hopefully delete again in
     the future (Kent)

   - deadline throttling fix (Zhiguo)

   - Series allowing building the kernel without buffer_head support
     (Christoph)

   - Sanitize the bio page adding flow (Christoph)

   - Write back cache fixes (Christoph)

   - MD updates via Song:
      - Fix perf regression for raid0 large sequential writes (Jan)
      - Fix split bio iostat for raid0 (David)
      - Various raid1 fixes (Heinz, Xueshi)
      - raid6test build fixes (WANG)
      - Deprecate bitmap file support (Christoph)
      - Fix deadlock with md sync thread (Yu)
      - Refactor md io accounting (Yu)
      - Various non-urgent fixes (Li, Yu, Jack)

   - Various fixes and cleanups (Arnd, Azeem, Chengming, Damien, Li,
     Ming, Nitesh, Ruan, Tejun, Thomas, Xu)"

* tag 'for-6.6/block-2023-08-28' of git://git.kernel.dk/linux: (113 commits)
  block: use strscpy() to instead of strncpy()
  block: sed-opal: keyring support for SED keys
  block: sed-opal: Implement IOC_OPAL_REVERT_LSP
  block: sed-opal: Implement IOC_OPAL_DISCOVERY
  blk-mq: prealloc tags when increase tagset nr_hw_queues
  blk-mq: delete redundant tagset map update when fallback
  blk-mq: fix tags leak when shrink nr_hw_queues
  ublk: zoned: support REQ_OP_ZONE_RESET_ALL
  md: raid0: account for split bio in iostat accounting
  md/raid0: Fix performance regression for large sequential writes
  md/raid0: Factor out helper for mapping and submitting a bio
  md raid1: allow writebehind to work on any leg device set WriteMostly
  md/raid1: hold the barrier until handle_read_error() finishes
  md/raid1: free the r1bio before waiting for blocked rdev
  md/raid1: call free_r1bio() before allow_barrier() in raid_end_bio_io()
  blk-cgroup: Fix NULL deref caused by blkg_policy_data being installed before init
  drivers/rnbd: restore sysfs interface to rnbd-client
  md/raid5-cache: fix null-ptr-deref for r5l_flush_stripe_to_raid()
  raid6: test: only check for Altivec if building on powerpc hosts
  raid6: test: make sure all intermediate and artifact files are .gitignored
  ...

Pull non-MM updates from Andrew Morton:

 - An extensive rework of kexec and crash Kconfig from Eric DeVolder
   ("refactor Kconfig to consolidate KEXEC and CRASH options")

 - kernel.h slimming work from Andy Shevchenko ("kernel.h: Split out a
   couple of macros to args.h")

 - gdb feature work from Kuan-Ying Lee ("Add GDB memory helper
   commands")

 - vsprintf inclusion rationalization from Andy Shevchenko
   ("lib/vsprintf: Rework header inclusions")

 - Switch the handling of kdump from a udev scheme to in-kernel
   handling, by Eric DeVolder ("crash: Kernel handling of CPU and memory
   hot un/plug")

 - Many singleton patches to various parts of the tree

* tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (81 commits)
  document while_each_thread(), change first_tid() to use for_each_thread()
  drivers/char/mem.c: shrink character device's devlist[] array
  x86/crash: optimize CPU changes
  crash: change crash_prepare_elf64_headers() to for_each_possible_cpu()
  crash: hotplug support for kexec_load()
  x86/crash: add x86 crash hotplug support
  crash: memory and CPU hotplug sysfs attributes
  kexec: exclude elfcorehdr from the segment digest
  crash: add generic infrastructure for crash hotplug support
  crash: move a few code bits to setup support of crash hotplug
  kstrtox: consistently use _tolower()
  kill do_each_thread()
  nilfs2: fix WARNING in mark_buffer_dirty due to discarded buffer reuse
  scripts/bloat-o-meter: count weak symbol sizes
  treewide: drop CONFIG_EMBEDDED
  lockdep: fix static memory detection even more
  lib/vsprintf: declare no_hash_pointers in sprintf.h
  lib/vsprintf: split out sprintf() and friends
  kernel/fork: stop playing lockless games for exe_file replacement
  adfs: delete unused "union adfs_dirtail" definition
  ...

Pull superblock updates from Christian Brauner:
 "This contains the super rework that was ready for this cycle. The
  first part changes the order of how we open block devices and allocate
  superblocks, contains various cleanups, simplifications, and a new
  mechanism to wait on superblock state changes.

  This unblocks work to ultimately limit the number of writers to a
  block device. Jan has already scheduled follow-up work that will be
  ready for v6.7 and allows us to restrict the number of writers to a
  given block device. That series builds on this work right here.

  The second part contains filesystem freezing updates.

  Overview:

  The generic superblock changes are rougly organized as follows
  (ignoring additional minor cleanups):

   (1) Removal of the bd_super member from struct block_device.

       This was a very odd back pointer to struct super_block with
       unclear rules. For all relevant places we have other means to get
       the same information so just get rid of this.

   (2) Simplify rules for superblock cleanup.

       Roughly, everything that is allocated during fs_context
       initialization and that's stored in fs_context->s_fs_info needs
       to be cleaned up by the fs_context->free() implementation before
       the superblock allocation function has been called successfully.

       After sget_fc() returned fs_context->s_fs_info has been
       transferred to sb->s_fs_info at which point sb->kill_sb() if
       fully responsible for cleanup. Adhering to these rules means that
       cleanup of sb->s_fs_info in fill_super() is to be avoided as it's
       brittle and inconsistent.

       Cleanup shouldn't be duplicated between sb->put_super() as
       sb->put_super() is only called if sb->s_root has been set aka
       when the filesystem has been successfully born (SB_BORN). That
       complexity should be avoided.

       This also means that block devices are to be closed in
       sb->kill_sb() instead of sb->put_super(). More details in the
       lower section.

   (3) Make it possible to lookup or create a superblock before opening
       block devices

       There's a subtle dependency on (2) as some filesystems did rely
       on fill_super() to be called in order to correctly clean up
       sb->s_fs_info. All these filesystems have been fixed.

   (4) Switch most filesystem to follow the same logic as the generic
       mount code now does as outlined in (3).

   (5) Use the superblock as the holder of the block device. We can now
       easily go back from block device to owning superblock.

   (6) Export and extend the generic fs_holder_ops and use them as
       holder ops everywhere and remove the filesystem specific holder
       ops.

   (7) Call from the block layer up into the filesystem layer when the
       block device is removed, allowing to shut down the filesystem
       without risk of deadlocks.

   (8) Get rid of get_super().

       We can now easily go back from the block device to owning
       superblock and can call up from the block layer into the
       filesystem layer when the device is removed. So no need to wade
       through all registered superblock to find the owning superblock
       anymore"

Link: https://lore.kernel.org/lkml/20230824-prall-intakt-95dbffdee4a0@brauner/

* tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (47 commits)
  super: use higher-level helper for {freeze,thaw}
  super: wait until we passed kill super
  super: wait for nascent superblocks
  super: make locking naming consistent
  super: use locking helpers
  fs: simplify invalidate_inodes
  fs: remove get_super
  block: call into the file system for ioctl BLKFLSBUF
  block: call into the file system for bdev_mark_dead
  block: consolidate __invalidate_device and fsync_bdev
  block: drop the "busy inodes on changed media" log message
  dasd: also call __invalidate_device when setting the device offline
  amiflop: don't call fsync_bdev in FDFMTBEG
  floppy: call disk_force_media_change when changing the format
  block: simplify the disk_force_media_change interface
  nbd: call blk_mark_disk_dead in nbd_clear_sock_ioctl
  xfs use fs_holder_ops for the log and RT devices
  xfs: drop s_umount over opening the log and RT devices
  ext4: use fs_holder_ops for the log device
  ext4: drop s_umount over opening the log device
  ...

Pull vfs timestamp updates from Christian Brauner:
 "This adds VFS support for multi-grain timestamps and converts tmpfs,
  xfs, ext4, and btrfs to use them. This carries acks from all relevant
  filesystems.

  The VFS always uses coarse-grained timestamps when updating the ctime
  and mtime after a change. This has the benefit of allowing filesystems
  to optimize away a lot of metadata updates, down to around 1 per
  jiffy, even when a file is under heavy writes.

  Unfortunately, this has always been an issue when we're exporting via
  NFSv3, which relies on timestamps to validate caches. A lot of changes
  can happen in a jiffy, so timestamps aren't sufficient to help the
  client decide to invalidate the cache.

  Even with NFSv4, a lot of exported filesystems don't properly support
  a change attribute and are subject to the same problems with timestamp
  granularity. Other applications have similar issues with timestamps
  (e.g., backup applications).

  If we were to always use fine-grained timestamps, that would improve
  the situation, but that becomes rather expensive, as the underlying
  filesystem would have to log a lot more metadata updates.

  This introduces fine-grained timestamps that are used when they are
  actively queried.

  This uses the 31st bit of the ctime tv_nsec field to indicate that
  something has queried the inode for the mtime or ctime. When this flag
  is set, on the next mtime or ctime update, the kernel will fetch a
  fine-grained timestamp instead of the usual coarse-grained one.

  As POSIX generally mandates that when the mtime changes, the ctime
  must also change the kernel always stores normalized ctime values, so
  only the first 30 bits of the tv_nsec field are ever used.

  Filesytems can opt into this behavior by setting the FS_MGTIME flag in
  the fstype. Filesystems that don't set this flag will continue to use
  coarse-grained timestamps.

  Various preparatory changes, fixes and cleanups are included:

   - Fixup all relevant places where POSIX requires updating ctime
     together with mtime. This is a wide-range of places and all
     maintainers provided necessary Acks.

   - Add new accessors for inode->i_ctime directly and change all
     callers to rely on them. Plain accesses to inode->i_ctime are now
     gone and it is accordingly rename to inode->__i_ctime and commented
     as requiring accessors.

   - Extend generic_fillattr() to pass in a request mask mirroring in a
     sense the statx() uapi. This allows callers to pass in a request
     mask to only get a subset of attributes filled in.

   - Rework timestamp updates so it's possible to drop the @now
     parameter the update_time() inode operation and associated helpers.

   - Add inode_update_timestamps() and convert all filesystems to it
     removing a bunch of open-coding"

* tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (107 commits)
  btrfs: convert to multigrain timestamps
  ext4: switch to multigrain timestamps
  xfs: switch to multigrain timestamps
  tmpfs: add support for multigrain timestamps
  fs: add infrastructure for multigrain timestamps
  fs: drop the timespec64 argument from update_time
  xfs: have xfs_vn_update_time gets its own timestamp
  fat: make fat_update_time get its own timestamp
  fat: remove i_version handling from fat_update_time
  ubifs: have ubifs_update_time use inode_update_timestamps
  btrfs: have it use inode_update_timestamps
  fs: drop the timespec64 arg from generic_update_time
  fs: pass the request_mask to generic_fillattr
  fs: remove silly warning from current_time
  gfs2: fix timestamp handling on quota inodes
  fs: rename i_ctime field to __i_ctime
  selinux: convert to ctime accessor functions
  security: convert to ctime accessor functions
  apparmor: convert to ctime accessor functions
  sunrpc: convert to ctime accessor functions
  ...

A syzbot stress test using a corrupted disk image reported that
mark_buffer_dirty() called from __nilfs_mark_inode_dirty() or
nilfs_palloc_commit_alloc_entry() may output a kernel warning, and can
panic if the kernel is booted with panic_on_warn.

This is because nilfs2 keeps buffer pointers in local structures for some
metadata and reuses them, but such buffers may be forcibly discarded by
nilfs_clear_dirty_page() in some critical situations.

This issue is reported to appear after commit 28a65b49eb53 ("nilfs2: do
not write dirty data after degenerating to read-only"), but the issue has
potentially existed before.

Fix this issue by checking the uptodate flag when attempting to reuse an
internally held buffer, and reloading the metadata instead of reusing the
buffer if the flag was lost.

Link: https://lkml.kernel.org/r/20230818131804.7758-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+cdfcae656bac88ba0e2d@syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/0000000000003da75f05fdeffd12@google.com
Fixes: 8c26c4e2694a ("nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption")
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org> # 3.10+
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

A syzbot stress test reported that create_empty_buffers() called from
nilfs_lookup_dirty_data_buffers() can cause a general protection fault.

Analysis using its reproducer revealed that the back reference "mapping"
from a page/folio has been changed to NULL after dirty page/folio gang
lookup in nilfs_lookup_dirty_data_buffers().

Fix this issue by excluding pages/folios from being collected if, after
acquiring a lock on each page/folio, its back reference "mapping" differs
from the pointer to the address space struct that held the page/folio.

Link: https://lkml.kernel.org/r/20230805132038.6435-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+0ad741797f4565e7e2d2@syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/0000000000002930a705fc32b231@google.com
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Use the generic setup_bdev_super helper to open the main block device
and do various bits of superblock setup instead of duplicating the
logic.  This includes moving to the new scheme implemented in common
code that only opens the block device after the superblock has allocated.

It does not yet convert nilfs2 to the new mount API, but doing so will
become a bit simpler after this first step.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Message-Id: <20230802154131.2221419-3-hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

During unmount process of nilfs2, nothing holds nilfs_root structure after
nilfs2 detaches its writer in nilfs_detach_log_writer().  Previously,
nilfs_evict_inode() could cause use-after-free read for nilfs_root if
inodes are left in "garbage_list" and released by nilfs_dispose_list at
the end of nilfs_detach_log_writer(), and this bug was fixed by commit
9b5a04ac3ad9 ("nilfs2: fix use-after-free bug of nilfs_root in
nilfs_evict_inode()").

However, it turned out that there is another possibility of UAF in the
call path where mark_inode_dirty_sync() is called from iput():

nilfs_detach_log_writer()
  nilfs_dispose_list()
    iput()
      mark_inode_dirty_sync()
        __mark_inode_dirty()
          nilfs_dirty_inode()
            __nilfs_mark_inode_dirty()
              nilfs_load_inode_block() --> causes UAF of nilfs_root struct

This can happen after commit 0ae45f63d4ef ("vfs: add support for a
lazytime mount option"), which changed iput() to call
mark_inode_dirty_sync() on its final reference if i_state has I_DIRTY_TIME
flag and i_nlink is non-zero.

This issue appears after commit 28a65b49eb53 ("nilfs2: do not write dirty
data after degenerating to read-only") when using the syzbot reproducer,
but the issue has potentially existed before.

Fix this issue by adding a "purging flag" to the nilfs structure, setting
that flag while disposing the "garbage_list" and checking it in
__nilfs_mark_inode_dirty().

Unlike commit 9b5a04ac3ad9 ("nilfs2: fix use-after-free bug of nilfs_root
in nilfs_evict_inode()"), this patch does not rely on ns_writer to
determine whether to skip operations, so as not to break recovery on
mount.  The nilfs_salvage_orphan_logs routine dirties the buffer of
salvaged data before attaching the log writer, so changing
__nilfs_mark_inode_dirty() to skip the operation when ns_writer is NULL
will cause recovery write to fail.  The purpose of using the cleanup-only
flag is to allow for narrowing of such conditions.

Link: https://lkml.kernel.org/r/20230728191318.33047-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+74db8b3087f293d3a13a@syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/000000000000b4e906060113fd63@google.com
Fixes: 0ae45f63d4ef ("vfs: add support for a lazytime mount option")
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org> # 4.0+
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Add a new config option that controls building the buffer_head code, and
select it from all file systems and stacking drivers that need it.

For the block device nodes and alternative iomap based buffered I/O path
is provided when buffer_head support is not enabled, and iomap needs a
a small tweak to define the IOMAP_F_BUFFER_HEAD flag to 0 to not call
into the buffer_head code when it doesn't exist.

Otherwise this is just Kconfig and ifdef changes.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20230801172201.1923299-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>